VFC^PLUS

VFC^PLUS is a high-performance control mode that can operate asynchronous motors and synchronous reluctance motors with very high torque dynamics with or without a rotary encoder.

The control mode VFC^PLUS can be operated as speed or torque control.

This control mode calculates all important state variables for controlling the motor by using a motor model.

For applications with a large speed setting range (especially for low speeds through to idle state) and high requirements regarding the control characteristics or for drives with high dynamic step changes in load, a motor encoder is absolutely necessary.

For applications with low requirements regarding the speed control characteristics and the torque dynamics, an encoder is not necessary. Without a rotary encoder, the electric rotor frequency is calculated in a model. In this case, stable stationary operation of the mode at low stator frequencies is not possible.

Due to the good torque dynamics, the VFC^PLUS control mode remains stable even in the event of sudden load changes and has a high torque accuracy. Typical applications for the VFC^PLUS control mode are speed-controlled asynchronous machines with high demands on the speed and torque stability.

Switching to a rotating motor is possible (flying start function).

A higher-level speed control loop that has to be parameterized accordingly is always used for speed control.

If the control mode is operated without an encoder, the actual speed of the motor is calculated by the control mode.

If an encoder is used, the angle information of this encoder is used for the control mode. The actual speed of the motor is calculated from this encoder. The maximum dynamics of the speed control loop are reached with a high-resolution encoder.

For asynchronous motors, only the relative rotor angle is necessary. In other words, an incremental encoder is sufficient. For synchronous reluctance motors, the VFC^PLUS control mode requires an encoder system that delivers the absolute position within one motor revolution. In the case of encoder types that do not provide an absolute position within one motor revolution, a commutation must be performed before every first enable after booting the system (FCB 18).

The torque control operating mode can be selected independently of an encoder and does not need an encoder. With an encoder, stable stationary operation at a stator frequency of 0 Hz is also possible.

A higher-level speed control loop that has to be parameterized accordingly is always used for torque control.

Position-controlled operation is only possible with an encoder, as the actual position is calculated from the parameterized encoder. This encoder can be mounted on the track or on the motor. The accuracy of the position control can be increased with a motor encoder.